When vacuuming the pool make sure the vac-hose is full of water before connecting it to the skimmer. You can remove the skimmer basket and connect the hose to the hole in the bottom of the skimmer or if you connect the hose to the vac-plate make sure the skimmer is full of water. Make sure the pump continues to pump water after the hose is connected before vacuuming the pool. You may need to empty the skimmer and/or pump baskets. You should vacuum on filter or waste only. When vacuuming on filter you may need to backwash and rinse after vacuuming 1/2 the pool. Do not vacuum the pool during the backwash and rinse. If the pool has algae or excessive debris you can vacuum on waste however the water level in the pool does go down when vacuuming on waste.